Detachable rock drill bit



Feb. 28, 1956 G. DIMITRIEFF 2,736,582

DETACHABLE ROCK DRILL BIT Filed Dec. 7, 1953 IN VEN TOR. Gearye Dimz'i'rz'cff United States Patent 2,736,582 DETACHABLE ROCK DRILL BITGeorge Dimltrielf, Noranda, Quebec, Canada Application December 7, 1953,Serial No. 396,559 1 Claim. (Cl. 287-126) This invention relates todetachable rock drill bits.

It is an object of this invention to provide a drill bit of thedetachable type wherein means are provided for locking the drill steelor rod to the bit whereby substantially no deformation stresses areimposed on the bit to permit convenient re-use of the latter.

It is a further object to provide a drill bit of the detachable typewherein means are provided for more positively locking the drill rodthereto in simple drive fit relation to the bit while permittingconvenient movement of such means to allow easy removal of the bit fromthe rod.

The invention will be described with reference to the accompanyingdrawing, in which:

Figure 1 is a sectional elevation of the bit in accordance with theinvention with a drill rod associated therewith, and

Figure 2 is a transverse sectional Figure 1.

In the drawing, 1 is a drill bit of generally conventional form having asocket 2, which may be of plain cylindrical form. The drill rod isindicated at 3 ventional form having a cylindrical socket-engaging shank4 of reduced cross-section and a tapered shoulder 5 at the juncture ofthe shank with the main portion of the drill rod.

The bit socket has a bottom wall surface 6, an interior side wallsurface 7 approximately perpendicular to the bottom surface 6, and anexterior side wall surface 8 approximately parallel to interior surface7. Surfaces 7 and 8 are thus parallel to the longitudinal axis of thebit. The cutting base portion 9 of the bit, as shown, flares outwardlyfrom the exterior surface 8 at a point slightly above the bottom surface6 of the socket. Thus, the depth of the exterior side wall surface 8 isslightly less than that of the interior side Wall surface 7.

In accordance with the invention, the bit socket wall is provided with alongitudinal slot 9, which preferably extends from the open mouth of thesocket throughout substantially the entire depth of exterior surface 8.In other words, the slot 9 terminates in somewhat spaced relation to thebottom wall surface 6 of the socket.

Surrounding the socket and snugly fitting the exterior wall surface 8thereof is a separate ring or annulus 10. The interior diameter of thering 10 is approximately view on line 2-2 of and is also of con-2,736,582 Patented Feb. 28, 1956 "ice equal to or but slightly greaterthan the normal exterior diameter of surface 8 to permit a snug,friction fit of the ring over the socket wall when the latter is freefrom engagement with the drill shank 4. The ring 10 has a depthapproximately equal to that of exterior surface 8.

In use, the detached bit is provided as described with the ring 10 inplace thereon, the snug fit of the ring being such that it rigidlyretains its position on the socket wall during handling. The shank ofthe drill rod or steel is inserted in the socket and driven to thebottom thereof. As shown in Figure 1, just prior to the shank reachingthe bottom of the socket, the shoulder 5 of the drill rod engages themouth of the socket wall and thus the further movement of the shank fromthis point to the bottom of the socket will expand both the socket sidewall and the ring 10. Because of the slot 9, the socket wall issubstantially freely expandable without imposition of permanentdeformation stresses thereon, such stresses being entirely imposed uponthe ring 10, which, it will be apparent, very positively locks the bitto the shank.

When the bit requires sharpening, it is readily removed from the drillrod following removal of the ring 10 therefrom by driving such ring 10off the socket wall. Since the socket wall of the bit has not beensubjected to any deformation stresses, the bit is ready for re-usefollowing sharpening simply by applying a new ring 10 thereto, thedeformed ring being discarded.

I claim:

In a rock drill including a drill rod having a body portion, acylindrical shank of less diameter than that of said body portion, and atapered shoulder joining said body portion and shank, a drill bit havingside and bottom walls forming a shank-receiving socket, the exteriorsurface of said side wall being substantially parallel to thelongitudinal axis of the bit, said side wall having a singlelongitudinal slot therein extending from the mouth of the socketsubstantially throughout the depth of said exterior surface, and a ringsurrounding said side wall and having a smooth exterior wall incompletely overlying relation to said slot, the normal unexpandedinterior diameter of said ring being approximately equal to the exteriordiameter of said side wall whereby to hold said ring in snugposition-retaining frictional engagement with said exterior surface,said exterior surface-and said ring each having a depth slightly lessthan the depth of said socket, the diameter of the socket beingapproximately equal to the diameter of said shank and said socketreceiving said shank in press fitting engagement therewith, the depth ofsaid socket being slightly greater than the length of said shank and theend of said side wall of the bit being engageable by said taperedshoulder to expand said side wall and ring.

References Cited in the file of this patent UNITED STATES PATENTS1,360,897 Dailey Nov. 30, 1920 2,246,670 Earl June 24, 1941 2,354,656Annesley Aug. 1, 1944

